LIGHT-INDUCED CAROTENE SYNTHESIS IN PHYCOMYCES

Blue light stimulates the synthesis of β-carotene in the fungus Phycomyces. It appears that the photoregulation of β-carotene synthesis in Phycomyces is under (at least) dual control. The dually controlled nature of light-induced β-carotene synthesis in Phycomyces is supported by: (1) the possible biphasic appearance of fluence-response data which suggest the superposition of two components, one responsive to low light fluence (saturation at ∼20 to 40 J/m2) and one responsive to high light fluence (saturating at ∼1000 J/m2); (2) the differential sensitivities of the low- and high-fluence components to the transcription and translation inhibitors, actinomycin D and cycloheximide, respectively; (3) the existence of mutants defective in the high-fluence component but normal in the low-fluence component. © 1979 Academic Press Inc. All rights reserved.